In recent years, plural telecommunications standards called third generation as high-speed CDMA mobile telecommunications methods are adopted as IMT-2000 by the International Telecommunications Union (ITU). According to the W-CDMA (FDD: Frequency Division Duplex) standard which is one of the plural telecommunications standards, commercial services were started in Japan in 2001. For the W-CDMA standard, the standardization organization 3GPP (3rd Generation Partnership Project) determined the first specifications to summarize them as the release 99th edition (Version name: 3.X.x) in 1999. Currently, release 4 and release 5 are specified as new versions of the release 99th edition, and release 6 is being examined and created.
Hereafter, main related channels will be explained below briefly. Physical-layer channels individually assigned to a mobile station as release-99-compliant channels include a DPCCH (Dedicated Physical Control CHannel) and a DPDCH (Dedicated Physical Data CHannel). The DPCCH is a channel via which various pieces of control information in a physical layer (e.g., a pilot signal for synchronization, a transmit-power-control signal, etc.) are transmitted.
The DPDCH is a channel via which various data from a MAC layer (Media Access Control layer: a protocol layer disposed above the physical layer) are transmitted. By the way, a channel used for delivery of data between the MAC layer and the physical layer is called a transport channel (Transport channel). In accordance with the release 99, a transport channel which corresponds to the DPDCH which is a physical-layer channel is called a DCH (Dedicated Channel). The above-mentioned DPCCH and DPDCH are set up for both uplink and downlink directions.
In accordance with the release 5, an HSDPA (High Speed Downlink Packet Access) technology is introduced in order to achieve an improvement in the efficiency of the packet transmission in the downlink, and, as physical-layer channels for the downlink, an HS-PDSCH (High Speed-Physical Downlink Shared CHannel) and an HS-SCCH (High Speed-Shared Control CHannel) are added. The HS-PDSCH and HS-SCCH can be used by two or more mobile stations. The HS-PDSCH is a channel via which data from the MAC layer are transmitted, like the DPDCH which complies with the release 99. The HS-SCCH is a channel via which control information (e.g., a modulation method of modulating the transmission data, the packet data size, etc.) at the time of transmitting data via the HS-PDSCH is transmitted. In accordance with release 5, an HS-DPCCH (High Speed-Dedicated Physical Control CHannel) is added as a physical-layer channel for the uplink. The mobile station transmits a reception judgment result (ACK/NACK) to the data sent thereto via the HS-PDSCH, and downlink radio environment information (CQI: Channel Quality Information) to the base station using the HS-DPCCH.
The release 99 is created by mainly assuming transmission and reception of continuous data like in the case of a voice call. Although an HSDPA which enables downlink high speed packet communications is added in the release 5, no specification assuming uplink high speed packet communications is created but the release 99 specification is applied just as it is. Therefore, also when carrying out burst (Burst) transmission from a mobile station to a base station as in the case of transmitting packet data, dedicated individual channels (DCH and DPDCH) must be always assigned to each mobile station. Therefore, by taking a status in which the demand for uplink packet data transmission is increasing with the proliferation of the Internet into consideration, there arises a problem from the viewpoint of the effective use of radio resources. Therefore, in the release 6, an introduction of an E-DCH (Enhanced DCH) technology is examined in order to implement the effective use of uplink radio resources and high-speed allocation of radio resources. The E-DCH technology may be called HSUPA (High Speed Uplink Packet Access).
In accordance with the E-DCH technology, an AMC (Adaptive Modulation and Coding) technology, an HARQ (Hybrid Automatic Repeat reQuest) technology, etc., which are, in the release 5, introduced with HSDPA, while a short transmission time interval (TTI: Transmission Time Interval) can be used. The E-DCH is a transport channel which is an extension of a DCH which is a transport channel which complies with the conventional standard, and is set up independently of the DCH. In accordance with the release 6, an E-DPDCH (Enhanced-DPDCH) and an E-DPCCH (Enhanced-DPCCH) are added as uplink physical channels for E-DCH. The E-DPDCH and the E-DPCCH are physical channels which correspond to a DPDCH and a DPCCH which comply with a standard prior to the release 5, and the E-DPDCH is a channel via which data from a MAC layer are transmitted and the E-DPCCH is a channel via which control information is transmitted. Furthermore, in the release 6, as downlink physical channels for E-DCH, an E-AGCH (Enhanced-Absolute Grant CHannel) and an E-RGCH (Enhanced-Relative Grant CHannel) via which scheduling results are notified, and an E-HICH (E-DCH HARQ Acknowledgement Indicator CHannel) via which a reception judgment result (ACK/NACK) is notified are added. The communications system as previously explained is disclosed in TS25.309v6.1.0 which is a specification of 3GPP created for E-DCH.    Nonpatent reference 1: 3rd Generation Partnership Project Technical Specification Group Radio Access Network; Feasibility Study for Enhanced Uplink for UTRA FDD (Release 6) 3GPP TS 25.309 V6.1.0 (2004-12)